1. Field of the Invention
This invention relates to a multi-layer structure roller and a method for producing the same, which is capable of being used for forming a roller used in order to carry out a polishing (gloss) process or an embossing (grained pattern) process on the surface of a thermoplastic resin sheet (or film) or a roller in order to make a film of an extremely thin film.
2. Description of the Related Art
Conventionally, when making or processing a film of a thermoplastic resin sheet (or film), especially, when forming a sheet by cool-caking the melted or softened resin film, and simultaneously, carrying out a polishing (gloss) process or an embossing (grained pattern) process, a rubber roller and a metal roller formed with a mirror face or an emboss face (a face having an asperities pattern) are used generally.
FIG. 6 shows a general situation when the process is carried out by using a metal roller 80 and a rubber roller 81 as described above. In the case of FIG. 6, a demineralizating-range or melted sheet is pressed between the metal roller 80 and the rubber roller 81 to be pressed with each of rollers 80 and 81, thereby the emboss pattern or polishing on the surface of the metal roller 80 is transferred onto the sheet 82. At this time, the rubber roller 81 is deformed elastically, whereby a surface-rolled area 84 formed by the metal roller 80 and the rubber roller 81, which sandwich the sheet 82, is to be surface-rolled.
The case of FIG. 6 has the following advantage. That is, generally, when the sheet is transferred by pressing between a combination of the higher-degree metal roller and the metal roller, the surface-rolled consists only of lines, whereby the transfer is not sufficient. However, in the case of FIG. 6, the surface-rolled area 84 is to be rolled because of the elastic deformation of the rubber roller, resulting in sufficient transfer.
As shown in FIG. 7, the process may be carried out by providing a metal-made endless belt 92 between a metal roller 90 and rubber roller 91. In FIG. 7, the metal-made endless belt 92 is wound and hitched between the rubber roller 91 and a cooling roller 93, in which the surface of the endless belt 92 is a mirror face or an emboss face. A sheet 94 is pressed between the rubber roller 91, wound with the endless belt 92, and the metal roller 90, having the mirror face or the emboss face. The endless belt 92, wound on the rubber roller 91, and the metal roller 90 are pressed on the sheet 94 to transfer the polishing or the emboss pattern on the metal roller 90 or the endless belt 92 onto the sheet. At this time, the rubber roller 91 is elastically deformed, with the result that a surface-rolled area 95, formed between the metal roller 90 and the endless belt 92 (the rubber roller 91) in the state that the sheet 94 is sandwiched between them, is to be surface-rolled. Therefore, the case shown in FIG. 7 has an advantage of obtaining sufficient transfer.
However, when the process is carried out by using the metal roller 80 and the rubber roller 81 as shown in FIG. 6, produces a disadvantage whereby the surface of the sheet 82 rolled with the rubber roller 81 becomes rough. Further, another disadvantage is produced, in which the sheet 82 is crumpled by increasing the temperature of the rubber roller 81, namely, deficiency by exfoliation of the sheet.
When the process is carried out by using the endless belt 92 as shown in FIG. 7, for the endless belt 92 as an intermediate, the sheet 94 and the rubber roller 91 are not directly rolled, resulting in no disadvantages such as deficiency by exfoliation or the rough face as shown in FIG. 6.
The method used for carrying out the process using the endless belt 92 as the intermediate is an extremely effective method, however, the method produces a disadvantage in that the apparatus increases in complexity and cost. Further, another disadvantage, a snake-inhibiting device for preventing the endless belt 92 from snaking, is needed. And still another disadvantage, the device has to be larger in order to increase the endurance of the endless belt 92.
It is extremely difficult to process the aforementioned precision emboss process (the emboss of about 10-100 .mu.) onto the metal roller or the surface of a metal plate. In some cases, only engraving onto the small area (e.g., 9 inch.times.9 inch) of the metal plate is possible, therefore, the engraved metal plate is used as a transferring plate or as an original plate of a replica in order to be used as the transferring plate replicated by, for example, electro-forming (a sculpturing method for correctly replicating the same metal model as the original plate by applying electroplated coatings).
The aforementioned transferring plates are all flat plates, thereby the micro-emboss sheet should be produced with use of a batch type of, for example, vacuum press, resulting in the disadvantage of critically low productivity.
As a consequence, in order to dramatically increase the productivity of the micro emboss sheet, a method has been required, in which the transferring plate of the flat plate is processed to a roller-shape to securely form a required micro emboss roller.